U.S. patent application number 14/178723 was filed with the patent office on 2015-02-12 for pattern formation method.
This patent application is currently assigned to Kabushiki Kaisha Toshiba. The applicant listed for this patent is Kabushiki Kaisha Toshiba. Invention is credited to Hirokazu KATO, Kentaro MATSUNAGA, Yoshihiro YANAI.
Application Number | 20150044874 14/178723 |
Document ID | / |
Family ID | 52449011 |
Filed Date | 2015-02-12 |
United States Patent
Application |
20150044874 |
Kind Code |
A1 |
MATSUNAGA; Kentaro ; et
al. |
February 12, 2015 |
PATTERN FORMATION METHOD
Abstract
According to one embodiment, a pattern formation method
includes: forming a first guide layer having of first openings
exposing a surface of an underlayer, and the first openings being
arranged in a first direction; forming a second guide layer on the
underlayer and on the first guide layer, the second guide layer
extending in the first direction, the second guide layer dividing
each of the first openings into the first opening portion and the
second opening portion, and the second guide layer being sandwiched
by a first opening portion and a second opening portion; forming a
block copolymer layer in each of the first opening portion and the
second opening portion; forming a first layer and a second layer
surrounded by the first layer in each of the first opening portion
and the second opening portion by phase-separating the block
copolymer layer; and removing the second layer.
Inventors: |
MATSUNAGA; Kentaro;
(Mie-ken, JP) ; YANAI; Yoshihiro; (Mie-ken,
JP) ; KATO; Hirokazu; (Aichi-ken, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kabushiki Kaisha Toshiba |
Minato-ku |
|
JP |
|
|
Assignee: |
Kabushiki Kaisha Toshiba
Minato-ku
JP
|
Family ID: |
52449011 |
Appl. No.: |
14/178723 |
Filed: |
February 12, 2014 |
Current U.S.
Class: |
438/702 |
Current CPC
Class: |
H01L 21/0337
20130101 |
Class at
Publication: |
438/702 |
International
Class: |
H01L 21/308 20060101
H01L021/308 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 7, 2013 |
JP |
2013-164026 |
Claims
1. A pattern formation method comprising: forming a first guide
layer on an underlayer, the first guide layer having a plurality of
first openings exposing a surface of the underlayer, and the
plurality of first openings being arranged in a first direction;
forming a second guide layer on the underlayer and on the first
guide layer, the second guide layer extending in the first
direction, the second guide layer dividing each of the plurality of
first openings into the first opening portion and the second
opening portion, and the second guide layer being sandwiched by a
first opening portion and a second opening portion; forming a block
copolymer layer in each of the first opening portion and the second
opening portion; forming a first layer and a second layer
surrounded by the first layer in each of the first opening portion
and the second opening portion by phase-separating the block
copolymer layer; and removing the second layer.
2. The pattern formation method according to claim 1, wherein a
width of each of the plurality of first openings in the first
direction is shorter than a width in a second direction crossing
the first direction.
3. The pattern formation method according to claim 1, wherein each
of the plurality of first openings is divided into the first
opening portion and the second opening portion in a second
direction crossing the first direction.
4. The pattern formation method according to claim 1, wherein a
height of the block copolymer layer is adjusted to the same height
as a height of the first guide layer.
5. The pattern formation method according to claim 1, wherein the
plurality of first openings have a first group aligned in the first
direction and a second group aligned in the first direction, a
phase of a period of positions of the plurality of first openings
of the first group and a phase of a period of positions of the
plurality of first openings of the second group are shifted from
each other, and the first group and the second group are
alternately arranged in the second direction crossing the first
direction.
6. The pattern formation method according to claim 5, wherein the
first group and the second group are formed by forming a plurality
of second openings in the first guide layer, the plurality of
second openings being aligned in the first direction and extending
in the second direction, each of the plurality of second openings
having a first region and a second region shifted in the first
direction from the first region, and forming a third guide layer
extending in the first direction on the underlayer and on the first
guide layer to separate the first region and the second region of
the plurality of second openings.
7. The pattern formation method according to claim 5, wherein a
pitch of the plurality of first openings of the first group and a
pitch of the plurality of first openings of the second group are
different in the first direction.
8. The pattern formation method according to claim 2, wherein the
plurality of first openings have a first group aligned in the first
direction and a second group aligned in the first direction, a
phase of a period of positions of the plurality of first openings
of the first group and a phase of a period of positions of the
plurality of first openings of the second group are shifted from
each other, and the first group and the second group are
alternately arranged in the second direction crossing the first
direction.
9. The pattern formation method according to claim 8, wherein the
first group and the second group are formed by forming a plurality
of second openings in the first guide layer, the plurality of
second openings being aligned in the first direction and extending
in the second direction, each of the plurality of second openings
having a first region and a second region shifted in the first
direction from the first region, and forming a third guide layer
extending in the first direction on the underlayer and on the first
guide layer to separate the first region and the second region of
the plurality of second openings.
10. The pattern formation method according to claim 8, wherein a
pitch of the plurality of first openings of the first group and a
pitch of the plurality of first openings of the second group are
different in the first direction.
11. The pattern formation method according to claim 1, wherein one
of a resist-containing layer and a carbon-containing layer is used
as the first guide layer.
12. The pattern formation method according to claim 2, wherein one
of a resist-containing layer and a carbon-containing layer is used
as the first guide layer.
13. The pattern formation method according to claim 5, wherein one
of a resist-containing layer and a carbon-containing layer is used
as the first guide layer.
14. The pattern formation method according to claim 1, wherein a
resist-containing layer is used as the second guide layer.
15. The pattern formation method according to claim 2, wherein a
resist-containing layer is used as the second guide layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2013-164026, filed on
Aug. 7, 2013; the entire contents of which are incorporated herein
by reference.
FIELD
[0002] Embodiments described herein relate generally to a pattern
formation method.
BACKGROUND
[0003] In a photolithography process, there is a case where
openings of the resolution limit or less are arranged
longitudinally and latitudinally (two-dimensionally) in a mask
layer. In such a case, what is called a cross-point method is
employed in which a line-and-space pattern used in exposure is
formed by two separate steps and photolithography is performed for
each step. Here, the line-and-space pattern used in the first
exposure and the line-and-space pattern used in the second exposure
are made to cross each other.
[0004] This method is most suitable to form an opening pattern of
what is called a grid configuration in which the phase of the
period of the positions of the openings is equal in the
longitudinal and latitudinal directions. However, to form an
opening pattern of a zigzag configuration in which the phases in
the longitudinal and latitudinal directions are shifted, three or
more line-and-space pattern formation processes are needed and the
processes are complicated. Consequently, manufacturing costs are
increased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a flow chart showing a pattern formation method
according to a first embodiment;
[0006] FIG. 2A to FIG. 7B are schematic plan views or schematic
cross-sectional views showing a pattern formation method according
to the first embodiment;
[0007] FIG. 8A to FIG. 8F are schematic plan views showing a
pattern formation method according to a reference example;
[0008] FIG. 9A to FIG. 11B are schematic plan views or schematic
cross-sectional views showing a pattern formation method according
to a second embodiment; and
[0009] FIG. 12A and FIG. 12B are schematic plan views showing a
pattern formation method according to a third embodiment.
DETAILED DESCRIPTION
[0010] In general, according to one embodiment, a pattern formation
method includes: forming a first guide layer on an underlayer, the
first guide layer having a plurality of first openings exposing a
surface of the underlayer, and the plurality of first openings
being arranged in a first direction; forming a second guide layer
on the underlayer and on the first guide layer, the second guide
layer extending in the first direction, the second guide layer
dividing each of the plurality of first openings into the first
opening portion and the second opening portion, and the second
guide layer being sandwiched by a first opening portion and a
second opening portion; forming a block copolymer layer in each of
the first opening portion and the second opening portion; forming a
first layer and a second layer surrounded by the first layer in
each of the first opening portion and the second opening portion by
phase-separating the block copolymer layer; and removing the second
layer.
[0011] Hereinbelow, embodiments are described with reference to the
drawings. In the following description, identical components are
marked with the same reference numerals, and a description of
components once described is omitted as appropriate.
First Embodiment
[0012] FIG. 1 is a flow chart showing a pattern formation method
according to a first embodiment.
[0013] FIG. 2A to FIG. 7B are schematic plan views or schematic
cross-sectional views showing a pattern formation method according
to the first embodiment.
[0014] FIG. 2A to FIG. 7B are a specific illustration of the flow
shown in FIG. 1. Of FIG. 2A to FIG. 7B, the drawings of the numbers
including "A" are schematic plan views, and the drawings of the
numbers including "B" are schematic cross-sectional views. The
drawings of the numbers including "B" show a cross section taken
along line A-B of the drawings of the numbers including "A".
[0015] First, as shown in FIG. 2A and FIG. 2B, a guide layer 20 (a
first guide layer) is formed on an underlayer 10A by
photolithography and dry etching (step S10 (FIG. 1)).
[0016] The guide layer 20 has a plurality of openings 21 that
expose the surface 10s of the underlayer 10A. The plurality of
openings 21 are arranged in the Y-direction (a first direction). In
the X-Y plane, the opening 21 is in an oval shape, for example. In
each of the plurality of openings 21, the width d1 in the
Y-direction is shorter than the width d2 in the X-direction (a
second direction) crossing the Y-direction.
[0017] The plurality of openings 21 have a first group 1G aligned
in the Y-direction and a second group 2G aligned in the
Y-direction. In the Y-direction, the phase of the period of the
positions of the plurality of openings 21 of the first group 1G and
the phase of the period of the positions of the plurality of
openings 21 of the second group 2G are shifted from each other. The
first group 1G and the second group 2G are alternately arranged in
the X-direction.
[0018] The number of openings 21 is not limited to the number
illustrated. Openings 21 may be arranged in the X-direction and the
Y-direction in a larger number than the number illustrated. In the
Y-direction, the pitch of the plurality of openings 21 of the first
group 1G and the pitch of the plurality of openings 21 of the
second group 2G do not necessarily need to be made to agree, and
the pitches may be different.
[0019] The underlayer 10A includes a substrate 11, a first hard
mask layer 12 provided on the substrate 11, a second hard mask
layer 13 provided on the first hard mask layer 12, and a reflection
prevention film 14 provided on the second hard mask layer 13.
[0020] The guide layer 20 includes a positive resist layer or a
negative resist layer, for example. The thickness of the guide
layer 20 is 120 nm (nanometers), for example. ArF light (e.g. ArF
excimer laser light) is used when the guide layer 20 is patterned.
Immersion exposure technology is used when the guide layer 20 is
patterned. An alkali solution of TMAH (tetramethylammonium
hydroxide) or the like is used in development after exposure.
Annealing treatment (e.g. 250.degree. C., 120 seconds) is performed
on the guide layer 20 in order to cure it, as necessary.
[0021] The substrate 11 is a semiconductor substrate of silicon or
the like, for example. The substrate 11 may be an insulating layer
such as an interlayer insulating film or a conductive layer. The
first hard mask layer 12 includes a carbon film, for example. The
thickness of the first hard mask layer 12 is 250 nm, for example.
The second hard mask layer 13 includes a silicon oxide film, for
example. The thickness of the second hard mask layer 13 is 50 nm,
for example. The first hard mask layer 12 and the second hard mask
layer 13 are formed by CVD (chemical vapor deposition), for
example.
[0022] The reflection prevention film 14 includes one of a silicon
oxide film, a carbon film, a stacked film of silicon oxide
film/carbon film, an organic film, and a metal film. The thickness
of the reflection prevention film 14 is 35 nm, for example. The
reflection prevention film 14 is formed by the application method
or CVD, for example. The reflection prevention film 14 may be
removed as necessary.
[0023] The stacked structure of the underlayer 10A described above
is only an example, and other stacked structures are possible.
[0024] Next, as shown in FIG. 3A and FIG. 3B, a guide layer 30 (a
second guide layer) is formed on the underlayer 10A and on the
guide layer 20 (step S20 (FIG. 1)). The guide layer 30 is formed by
photolithography and dry etching. The photolithography and dry
etching in this stage correspond to the second photolithography and
dry etching in the flow shown in FIG. 2A to FIG. 7B.
[0025] The guide layer 30 includes a positive resist layer, for
example. The material of the guide layer 30 is the same as the
material of the guide layer 20, for example. The first embodiment
illustrates the case where both the guide layers 20 and 30 are a
positive resist layer, as an example.
[0026] The guide layer 30 extends in the Y-direction. Each of the
plurality of openings 21 is divided into an opening portion 21a (a
first opening portion) and an opening portion 21b (a second opening
portion) by the guide layer 30. The guide layer 30 is sandwiched by
the opening portion 21a and the opening portion 21b.
[0027] In this stage, the opening portion 21a and the opening
portion 21b, which are smaller than the opening 21, are formed.
Each of the opening portion 21a and the opening portion 21b is
surrounded by the guide layer 20 and the guide layer 30 in the X-Y
plane (FIG. 3A). The underlayer 10A is exposed from each of the
opening portion 21a and the opening portion 21b. The plurality of
opening portions have a first group 1g aligned in the Y-direction
and a second group 2g of which the phase of the positions is
shifted from that of the first group 1g. For example, in the
Y-direction, the phase of the period of the positions of the
plurality of opening portions 21a of the first group 1g and the
phase of the period of the positions of the plurality of opening
portions 21b of the second group 2g are shifted from each
other.
[0028] Next, as shown in FIG. 4A and FIG. 4B, a block copolymer
layer 40 is formed in each of the opening portion 21a and the
opening portion 21b (step S30 (FIG. 1)).
[0029] The block copolymer layer 40 contains a polystyrene
derivative, poly(methyl methacrylate) (an acrylic), and an organic
solvent that can dissolve these polymer materials, for example. The
block copolymer layer 40 is formed in the opening portion 21a and
the opening portion 21b by the spin coating method, for example.
The height of the block copolymer layer 40 is adjusted to the same
height as the height of the guide layer 20.
[0030] Next, as shown in FIG. 5A and FIG. 5B, the block copolymer
layer 40 is heated to be microphase-separated. The heating
treatment is 250.degree. C. and 60 seconds, for example. Thereby, a
first layer 41 and a second layer 42 surrounded by the first layer
41 are formed in each of the opening portion 21a and the opening
portion 21b (step S40 (FIG. 1)). That is, a self-assembled layer 43
including the first layer 41 and the second layer 42 is formed in
each of the opening portion 21a and the opening portion 21b. The
organic solvent contained in the block copolymer layer 40 is
vaporized by the heating.
[0031] Here, the first layer 41 is a layer containing a polystyrene
derivative, and the second layer 42 is a layer containing
poly(methyl methacrylate).
[0032] The self-assembled layer 43 is a layer formed by
microphase-separating a block copolymer by heating. It is assumed
that the block copolymer includes two kinds of polymers A and B,
for example. In the case where the affinity of the polymer A to the
guide layers 20 and 30 is higher than the affinity of the polymer B
to the guide layers 20 and 30, the polymer A is more likely to
gather at the side walls of the guide layers 20 and 30 than the
polymer B after microphase separation. Subsequently, the polymer B
gathers at the side wall of the polymer A. Thereby, in the X-Y
plane, A and B are self-arranged, and polymers are arranged
regularly in the order of AB from the side walls of the guide
layers 20 and 30. In other words, the first layer 41 of a cylinder
structure and the second layer 42 surrounded by the first layer 41
are formed.
[0033] In the case where the block copolymer includes polystyrene
(PS)-poly(methyl methacrylate) (PMMA), the affinity of the
polystyrene derivative to the guide layers 20 and 30 is higher than
the affinity of the poly(methyl methacrylate) to the guide layers
20 and 30, for example. Thus, for the polymers A and B mentioned
above, the polymer A corresponds to polystyrene (PS), and the
polymer B corresponds to poly(methyl methacrylate) (PMMA).
[0034] Next, as shown in FIG. 6A and FIG. 6B, the second layer 42
is removed (step S50 (FIG. 1)). For example, the second layer 42
having lower dry etching resistance than the first layer 41 is
removed by dry etching. After the dry etching, the first layer 41
in contact with the guide layers 20 and 30 is left.
[0035] Subsequently, the guide layers 20 and 30 and the first layer
41 are used as a mask layer 50 to perform dry etching processing on
the reflection prevention film 14 exposed from the mask layer 50,
the second hard mask layer 13 directly under this reflection
prevention film 14, and the first hard mask layer 12 directly under
this second hard mask layer 13. In other words, the pattern of the
mask layer 50 is transferred to the reflection prevention film 14,
the second hard mask layer 13, and the first hard mask layer 12.
FIG. 7A and FIG. 7B show this state.
[0036] As shown in FIG. 7A and FIG. 7B, the first hard mask layer
12 and the second hard mask layer 13 in which the pattern of the
mask layer 50 is transferred are formed on the substrate 11. A hard
mask layer 15 including the first hard mask layer 12 and the second
hard mask layer 13 has a plurality of openings 16. The plurality of
openings 16 are arranged in a zigzag configuration in the X-Y
plane.
[0037] Here, the openings arranged in a zigzag configuration refer
to openings in a state where, when a group of two columns of
openings aligned in the X-direction, for example, are arbitrarily
selected in the X-Y plane, the phases of the periods of the
positions of the openings in this group of two columns are shifted
from each other. In the case where the phases of the periods of the
positions of the openings in the group of two columns agree with
each other in the X-direction, the openings are referred to as
openings arranged in a lattice configuration (or a grid
configuration).
[0038] The width d3 in the Y-direction of each of the plurality of
openings 16 is narrower than the width d1 in the Y-direction of the
opening 21. The width d4 in the X-direction of each of the
plurality of openings 16 is narrower than the width d2 in the
X-direction of the opening 21. This is because the first hard mask
layer 12 and the second hard mask layer 13 have been processed by
dry etching while the first layer 41 out of the first layer 41 and
the second layer 42 formed by microphase separation is left. That
is, by the first embodiment, a finer opening pattern can be
formed.
[0039] After that, the hard mask layer 15 having the plurality of
openings 16 may be used to perform the dry etching processing of
the substrate 11. In other words, the pattern of the hard mask
layer 15 can be transferred to the substrate 11.
[0040] Also an example in which the guide layers 20 and 30 are
formed using a negative resist layer is included in the embodiment.
Even when such a selection is made, the effects of the embodiment
are not changed. In the case where the guide layers 20 and 30 are
formed using a negative resist layer, a butyl acetate solution is
used as the developer.
[0041] A process in which a mask layer having openings arranged in
a zigzag configuration is formed without using the block copolymer
layer 40 will now be described.
[0042] FIG. 8A to FIG. 8F are schematic plan views showing a
pattern formation method according to a reference example.
[0043] FIG. 8A to FIG. 8F show a reference example in which an
opening pattern of a zigzag configuration is formed.
[0044] First, as shown in FIG. 8A, a plurality of mask layers 100
are formed on the underlayer 10A by the first photolithography and
dry etching. The plurality of mask layers 100 extend in the
X-direction, and are arranged in the Y-direction.
[0045] Next, as shown in FIG. 8B, a plurality of mask layers 101
are formed on the underlayer 10A by the second photolithography and
dry etching. The plurality of mask layers 100 extend in the
Y-direction, and are arranged in the X-direction. In other words,
the mask layer 101 is made to cross the mask layer 100.
[0046] Next, as shown in FIG. 8C, dry etching processing is
performed on the underlayer 10A exposed from the mask layers 100
and 101. After that, the mask layers 100 and 101 are removed.
Thereby, a hard mask layer 15 in which openings 16 are arranged in
the X-direction and the Y-direction is formed. At this stage, the
openings 16 are arranged in a lattice configuration.
[0047] Next, as shown in FIG. 8D, a plurality of mask layers 102
are formed on the hard mask layer 15 by the third photolithography
and dry etching. The plurality of mask layers 102 extend in the
X-direction, and are arranged in the Y-direction. Each of the
plurality of mask layers 102 seals the opening 16.
[0048] Next, as shown in FIG. 8E, a plurality of mask layers 103
are formed on the hard mask layer 15 by the fourth photolithography
and dry etching. The plurality of mask layers 103 extend in the
Y-direction, and are arranged in the X-direction. Each of the
plurality of mask layers 103 seals the opening 16. The mask layer
103 is made to cross the mask layer 102. In other words, portions
of the surface of the hard mask layer 15 where the opening 16 is
not formed are exposed by the mask layers 102 and 103.
[0049] Next, as shown in FIG. 8F, dry etching processing is
performed on the hard mask layer 15 exposed from the mask layers
102 and 103. After that, the mask layers 102 and 103 are removed.
Thereby, a hard mask layer 15 in which new openings 16 are arranged
in the X-direction and the Y-direction is formed.
[0050] Here, it can be seen that FIG. 8F shows a state where the
opening pattern shown in FIG. 8C and the opening pattern formed by
the dry etching processing of FIG. 8F are added up. Also in the
pattern formation method according to the reference example, an
opening pattern arranged in a zigzag configuration is formed.
[0051] However, in the pattern formation method according to the
reference example, the number of photolithography processes and the
number of dry etching processes when mask layers are formed are
each as large as four (FIG. 8A, FIG. 8B, FIG. 8D, and FIG. 8E).
Therefore, in the reference example, the number of manufacturing
processes is increased as compared the first embodiment, and
manufacturing costs are increased.
[0052] In contrast, in the first embodiment, the number of
photolithography processes and the number of dry etching processes
when mask layers are formed are each only two, which are the
photolithography and dry etching when the guide layer 20 is formed
and the photolithography and dry etching when the guide layer 30 is
formed (FIGS. 2A and 2B and FIGS. 3A and 3B). Therefore, the number
of manufacturing processes is reduced as compared to the reference
example, and manufacturing costs can be reduced.
[0053] Furthermore, in the first embodiment, openings are formed
using the technology of microphase-separating a block copolymer.
Therefore, minute openings can be formed in a mask layer.
[0054] Furthermore, in the first embodiment, in the stage of
forming the guide layer 20, an opening pattern can be prepared in
which the pitch of the plurality of openings 21 of the first group
1G in the Y-direction and the pitch of the plurality of openings 21
of the second group 2G in the Y-direction are different. By
preparing such an opening pattern beforehand, the pitch of the
plurality of opening portions 21a of the first group 1g in the
Y-direction and the pitch of the plurality of opening portions 21b
of the second group 2g in the Y-direction can be differentiated,
even for opening portions 21a and 21b that are processed more
finely.
Second Embodiment
[0055] The guide layer does not need to be a resist-containing
layer, and may be a silicon-containing layer.
[0056] FIG. 9A to FIG. 11B are schematic plan views or schematic
cross-sectional views showing a pattern formation method according
to a second embodiment.
[0057] Of FIG. 9A to FIG. 11B, the drawings of the numbers
including "A" are schematic plan views, and the drawings of the
numbers including "B" are schematic cross-sectional views. The
drawings of the numbers including "B" show a cross section taken
along line A-B of the drawings of the numbers including "A".
[0058] First, as shown in FIG. 9A and FIG. 9B, a carbon-containing
layer 17 is formed on an underlayer 10B, and a silicon-containing
layer 18 is formed on the carbon-containing layer 17. The
carbon-containing layer 17 is an SOC (spin on carbon) layer, for
example. The silicon-containing layer 18 is an SOG (spin on glass)
layer, for example. Subsequently, a mask layer 60 is formed on the
silicon-containing layer 18 by photolithography and dry
etching.
[0059] The thickness of the carbon-containing layer 17 is 120 nm,
for example. The thickness of the silicon-containing layer 18 is 30
nm. The optical constants and the film thicknesses of the
carbon-containing layer 17 and the silicon-containing layer 18 are
adjusted so that the stacked film of these layers forms a
reflection prevention film to ArF light.
[0060] The mask layer 60 has a plurality of openings 61 that expose
the surface 18s of the silicon-containing layer 18. The mask layer
60 includes a positive resist layer. The thickness of the mask
layer 60 is 80 nm. The plurality of openings 61 are arranged in the
Y-direction. In the X-Y plane, the shape of the opening 61 is the
same as that of the opening 21.
[0061] The plurality of openings 61 have a first group 1G aligned
in the Y-direction and a second group 2G aligned in the
Y-direction. In the Y-direction, the phase of the period of the
positions of the plurality of openings 61 of the first group 1G and
the phase of the period of the positions of the plurality of
openings 61 of the second group 2G are shifted from each other. The
first group 1G and the second group 2G are alternately arranged in
the X-direction.
[0062] The number of openings 61 is not limited to the number
illustrated. In the Y-direction, the pitch of the plurality of
openings 61 of the first group 1G and the pitch of the plurality of
openings 61 of the second group 2G do not necessarily need to be
made to agree, and the pitches may be different.
[0063] The underlayer 10B includes the substrate 11, the first hard
mask layer 12 provided on the substrate 11, and the second hard
mask layer 13 provided on the first hard mask layer 12. The
thickness of the first hard mask layer 12 is 400 nm, for example.
The thickness of the second hard mask layer 13 is 100 nm, for
example.
[0064] The optical constants and the film thicknesses of the first
hard mask layer 12 and the second hard mask layer 13 are adjusted
so that the stacked film of these layers forms a reflection
prevention film to ArF light.
[0065] Subsequently, dry etching processing is performed on the
silicon-containing layer 18 exposed from the mask layer 60 and the
carbon-containing layer 17 directly under this silicon-containing
layer 18. After that, the mask layer 60 is removed. FIG. 10A and
FIG. 10B show this state.
[0066] As shown in FIG. 10A and FIG. 10B, the carbon-containing
layer 17 has a plurality of openings 19 that expose the surface 10s
of the underlayer 10B. The plurality of openings 19 are arranged in
the Y-direction. In the X-Y plane, the shape of the opening 19 is
the same as that of the opening 61.
[0067] The plurality of openings 19 have a first group 1G aligned
in the Y-direction and a second group 2G aligned in the
Y-direction. In the Y-direction, the phase of the period of the
positions of the plurality of openings 19 of the first group 1G and
the phase of the period of the positions of the plurality of
openings 19 of the second group 2G are shifted from each other. The
first group 1G and the second group 2G are alternately arranged in
the X-direction. After that, the silicon-containing layer 18 is
removed.
[0068] Next, as shown in FIG. 11A and FIG. 11B, the guide layer 30
is formed on the underlayer 10B and on the carbon-containing layer
17. The guide layer 30 is formed by photolithography and dry
etching. The guide layer 30 includes a positive resist layer, for
example.
[0069] The guide layer 30 extends in the Y-direction. Each of the
plurality of openings 19 is divided into an opening portion 19a and
an opening portion 19b by the guide layer 30. The guide layer 30 is
sandwiched by the opening portion 19a and the opening portion
19b.
[0070] In this stage, the opening portion 19a and the opening
portion 19b, which are a smaller opening than the opening 19, are
formed. In the second embodiment, the carbon-containing layer 17
functions as a guide layer. In other words, each of the opening
portion 19a and the opening portion 19b is surrounded by the
carbon-containing layer 17, which is a guide layer, and the guide
layer 30 in the X-Y plane (FIG. 11A). The underlayer 10B is exposed
from each of the opening portion 19a and the opening portion 19b.
The plurality of opening portions have a first group 1g aligned in
the Y-direction and a second group 2g of which the phase of the
positions is shifted from that of the first group 1g. For example,
in the Y-direction, the phase of the period of the positions of the
plurality of opening portions 19a of the first group 1g and the
phase of the period of the positions of the plurality of opening
portions 19b of the second group 2g are shifted from each
other.
[0071] After that, similarly to the first embodiment, the block
copolymer layer 40 is formed in each of the opening portions 19a
and 19b. Then, the block copolymer layer 40 is
microphase-separated. After that, similarly to the first
embodiment, the pattern of the opening portions 19a and 19b is
transferred to the first hard mask layer 12 and the second hard
mask layer 13. Also in the second embodiment, similar effects to
the first embodiment are obtained.
Third Embodiment
[0072] When openings 21 are formed in the guide layer 20, a reticle
having a pattern corresponding to the pattern of the openings 21
may be used to transfer the pattern of the openings 21 to the guide
layer 20 by one shot. Further, the openings 21 may be formed in the
guide layer 20 by the following process.
[0073] FIG. 12A and FIG. 12B are schematic plan views showing a
pattern formation method according to a third embodiment.
[0074] As shown in FIG. 12A, a plurality of openings 21L are formed
in the guide layer 20 by photolithography and dry etching. Each of
the plurality of openings 21L is a trench-like opening. The
plurality of openings 21L extend in the X-direction, and are
aligned in the Y-direction.
[0075] However, the opening 21L extending in the X-direction does
not extend rectilinearly in the X-direction, and is in a wave form
in the X-Y plane. For example, the opening 21L forms a wave in
which an .alpha. portion of the opening 21L and a .beta. portion of
the opening 21L that is shifted in the -Y-direction from the
.alpha. portion constitute one wavelength.
[0076] Next, as shown in FIG. 12B, a guide layer 31 extending in
the Y-direction is formed on the underlayer 10A and on the guide
layer 20. The .alpha. portion of the opening 21L and the .beta.
portion of the opening 21L are separated by the guide layer 31.
[0077] That is, by separating the .alpha. portion of the opening
21L and the .beta. portion of the opening 21L, the guide layer 20
has a plurality of openings 21 that expose the underlayer 10A. The
plurality of openings 21 are arranged in the Y-direction. In each
of the plurality of openings 21, the width d1 in the Y-direction is
shorter than the width d2 in the X-direction.
[0078] The plurality of openings 21 have a first group 1G aligned
in the Y-direction and a second group 2G aligned in the
Y-direction. In the Y-direction, the phase of the period of the
positions of the plurality of openings 21 of the first group 1G and
the phase of the period of the positions of the plurality of
openings 21 of the second group 2G are shifted from each other. The
first group 1G and the second group 2G are alternately arranged in
the X-direction. Also by such a process, a plurality of openings 21
can be formed in the guide layer 20.
[0079] The term "on" in "a portion A is provided on a portion B"
refers to the case where the portion A is provided on the portion B
such that the portion A is in contact with the portion B and the
case where the portion A is provided above the portion B such that
the portion A is not in contact with the portion B. The term "on"
in "a portion A is provided on a portion B" refers to the case
where the portion A is provided under the portion B such that the
portion A and the portion B are turned upside down and the portion
A comes abreast of the portion B. This is because that, if the
semiconductor device according to embodiments are rotated, the
structure of the semiconductor device remains unchanged before and
after rotation.
[0080] The embodiments have been described above with reference to
examples. However, the embodiments are not limited to these
examples. More specifically, these examples can be appropriately
modified in design by those skilled in the art. Such modifications
are also encompassed within the scope of the embodiments as long as
they include the features of the embodiments. The components
included in the above examples and the layout, material, condition,
shape, size and the like thereof are not limited to those
illustrated, but can be appropriately modified.
[0081] Furthermore, the components included in the above
embodiments can be combined as long as technically feasible. Such
combinations are also encompassed within the scope of the
embodiments as long as they include the features of the
embodiments. In addition, those skilled in the art could conceive
various modifications and variations within the spirit of the
embodiments. It is understood that such modifications and
variations are also encompassed within the scope of the
embodiments.
[0082] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in
the form of the embodiments described herein may be made without
departing from the spirit of the inventions. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
invention.
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